Cervical cancer is the second most common cancer diagnosis in women and is linked to high-risk human papillomavirus infection 99.7% of the time. Currently, 12,000 new cases of invasive cervical cancer are diagnosed in US women annually, resulting in 5,000 deaths each year. Furthermore, there are approximately 400,000 cases of cervical cancer and close to 200,000 deaths annually worldwide. Human papillomaviruses (HPVs) are one of the most common causes of sexually transmitted disease in the world. Overall, 50-75% of sexually active men and women acquire genital HPV infections at some point in their lives. An estimated 5.5 million people become infected with HPV each year in the US alone, and at least 20 million are currently infected. The more than 100 different isolates of HPV have been broadly subdivided into high-risk and low-risk subtypes based on their association with cervical carcinomas or with benign cervical lesions or dysplasias.
A number of lines of evidence point to HPV infections as the etiological agents of cervical cancers. Multiple studies in the 1980's reported the presence of HPV variants in cervical dysplasias, cancer, and in cell lines derived from cervical cancer. Further research demonstrated that the E6-E7 region of the genome from oncogenic HPV 18 is selectively retained in cervical cancer cells, suggesting that HPV infection could be causative and that continued expression of the E6-E7 region is required for maintenance of the immortalized or cancerous state. The following year, Sedman et al demonstrated that the E6-E7 genes from HPV 16 were sufficient to immortalize human keratinocytes in culture. Barbosa et al demonstrated that although E6-E7 genes from high risk HPVs could transform cell lines, the E6-E7 regions from low risk, or non-oncogenic variants such as HPV 6 and HPV 11 were unable to transform human keratinocytes. More recently, Pillai et al examined HPV 16 and 18 infection by in situ hybridization and E6 protein expression by immunocytochemistry in 623 cervical tissue samples at various stages of tumor progression and found a significant correlation between histological abnormality and HPV infection.
Current treatment paradigms are focused on the actual cervical dysplasia rather than the underlying infection with HPV. Women are screened by physicians annually for cervical dysplasia and are treated with superficial ablative techniques, including cryosurgery, laser ablation and excision. As the disease progresses, treatment options become more aggressive, including partial or radical hysterectomy, radiation or chemotherapy. A significant unmet need exists for early and accurate diagnosis of oncogenic HPV infection as well as for treatments directed at the causative HPV infection, preventing the development of cervical cancer by intervening earlier in disease progression. Human papillomaviruses characterized to date are associated with lesions confined to the epithelial layers of skin, or oral, pharyngeal, respiratory, and, most importantly, anogenital mucosae. Specific human papillomavirus types, including HPV 6 and 11, frequently cause benign mucosal lesions, whereas other types such as HPV 16, 18, and a host of other strains, are predominantly found in high-grade lesions and cancer. Individual types of human papillomaviruses (HPV) which infect mucosal surfaces have been implicated as the causative agents for carcinomas of the cervix, anus, penis, larynx and the buccal cavity, occasional periungal carcinomas, as well as benign anogenital warts. The identification of particular HPV types is used for identifying patients with premalignant lesions who are at risk of progression to malignancy. Although visible anogenital lesions are present in some persons infected with human papillomavirus, the majority of individuals with HPV genital tract infection do not have clinically apparent disease, but analysis of cytomorphological traits present in cervical smears can be used to detect HPV infection. Papanicolaou tests are a valuable screening tool, but they miss a large proportion of HPV-infected persons due to the unfortunate false positive and false negative test results. In addition, they are not amenable to worldwide testing because interpretation of results requires trained pathologists.
Conventional viral detection assays, including serologic assays, sandwich ELISA assays and growth in cell culture, are not commercially available and/or are not suitable for the diagnosis and tracking of HPV infection. Recently, several PCR (polymerase chain reaction)-based tests for HPV infections have become available. Though the tests provide the benefit of differentiating oncogenic from non-oncogenic infections, they are fairly expensive to administer and require highly trained technicians to perform PCR and/or luminometer assays. In addition, PCR has a natural false positive rate that may invoke further testing or procedures that are not required. Since the oncogenicity of HPV has been shown to be protein based, early detection of HPV DNA or RNA may lead to unnecessary medical procedures that the body's immune system may solve naturally.
The difficulties in detecting oncogenic HPV in human samples (e.g., a sample of a tumor) using traditional methods are numerous. For example, detection of E6 protein using antibodies is difficult because E6 that is made in a human cell contains a number of structural modifications, e.g., disulfide bonds and phosphate groups, that cause wild-type E6 protein made in bacterial systems, or chemically synthesized E6 peptides, to not recognize E6 protein in human cells. Further, since oncogenic E6 proteins do not share an epitope that distinguishes them from non-oncogenic E6 proteins, a single antibody cannot be used for the detection of all oncogenic E6 HPV strains.
The detection and diagnosis of disease is a prerequisite for the treatment of disease. Numerous markers and characteristics of diseases have been identified and many are used for the diagnosis of disease. Many diseases are preceded by, and are characterized by, changes in the state of the affected cells. Changes can include the expression of pathogen genes or proteins in infected cells, changes in the expression patterns of genes or proteins in affected cells, and changes in cell morphology. The detection, diagnosis, and monitoring of diseases can be aided by the accurate assessment of these changes. Inexpensive, rapid, early and accurate detection of pathogens can allow treatment and prevention of diseases that range in effect from discomfort to death.
The following publications are of interest: Munger (2002) Front. Biosci. 7:d641-9; Glaunsinger (2000) Oncogene 19:5270-80; Gardiol (1999) Oncogene 18:5487-96; Pim (1999) Oncogene 18:7403-8; Meschede (1998) J. Clin. Microbiol. 36:475-80; Kiyono (1997) Proc. Natl. Acad. Sci. 94:11612-6; and Lee (1997) Proc. Natl. Acad. Sci. 94:6670-5. In addition, the following patents and patent applications are of interest: Bleul, U.S. Pat. No. 6,322,794; Cole, U.S. Pat. No. 6,344,314; Schoolnik, U.S. Pat. No. 5,415,995; Bleul, U.S. Pat. No. 5,753,233; Cole, U.S. Pat. No. 5,876,723; Cole, U.S. Pat. No. 5,648,459; Orth, U.S. Pat. No. 6,391,539; Orth, U.S. Pat. No. 5,665,535; Schoolnik, U.S. Pat. No. 4,777,239.